Method and means for determining the error in watches, clocks, and other devices



May 10,1927. 1,628,214

E. WOLF METHOD AND MEANS FOR DETERMINING THE ERROR IN WATCHES, CLOCKS, AND OTHER DEVICES Filed Dec. 1921 2 Sheets-Sheet l ay E. WOLF v METHOD AND MEANS. FOR DETERMINING THE ERROR IN WATCHES, CLOCKS, AND OTHER DEVICES Filed Dec. 1 1921 1 2 Sheets-Sheet 2 Y /7' TU Ways:

' Patented wig-10,1927. UNITED STATES 1,628,214 PATENT OFFICE.

EZEKIEL WOLF, or Ros oN, MA SACHUSETTS, ASSIGNOR, BY MEs NE ASSIGNMENTS,

' To HAMMOND v. HAYES, TRUSTEE, 013 BOSTON, MASSACHUSETTS.

METHOD AND MEANS FOR DETERMINING THE ERROR IN WATCHES, Crooks, AND

OTHER DEVICES.

Application filed December 16, 1921. Serial No. 522,853.

I-Ieretofore when a watch or similar device, particularly when new and unregulated, is to be tested for its accuracy in meas- "uring time, it has been'necessary to set it to the same time=as that given by a chronOmete and to note the accumulated error 1 shown by the difference in the times indicated by the watch and chronometer after the lapse of a considerable interval of time. The elapsed time involved in showing this accumulated error varies with the accuracy of'the device under test. ranging from possibly fifteen minutes with an unregulated watch to perhaps twenty-four hours with a watch which is running fairly accurately. After the inaccuracy has been ascertained in i this manner the Watch is regulated and the same process must be repeated until the accumulated error. is shown to be within the required limit of accuracy.

Considerable time is thus occupied in carrying out the above method of regulatiml;

By the use of the method hereinafter der;

scribed'it is possible to obtain a knowledge of whether a watch is running fast or slow almost instantly and to give a fair figure for its inaccuracy in a short time, probablyin a majority of the trials within one minute, and the complete regulation of a watch can be performed in practically one operation.

In the drawingsis shown my invention embodied in its preferred form.

Fi re 1 shows in side elevation the preferred form of mechanism used in carrying out my invention. Fig. 2 shows in front elevation the rotating diskcarrying a terminal,

Fig. 3 Shows in front elevation the stationary disk and adjustable pointer.

Fig. 4 shows the observing instrument in longitudinal section arranged to observe the action of the hair spring of a watch.

Fig. 5 shows a modification adapted to utilize the binaural method of comparing the time intervals.

In Fig. 1, 1 is a synchronous electric motor, the speed of which is absolutely controlled in a way well known as by a chronometer mechanism. Fixed upon the motor shaft 2 are gears 3, 3 and 3 each of which may be engaged at the will of the observer by corresponding gears 4, 4' and 4', Slidable on the shaft 5 which turns freely on support support 9. An arm 14 is fastened rigidly upon shaft 10 and has near its end a terminal contact 15 which, for an instant, in every-revolution of rotating disk 7 is engaged by contact 8. These contacts 8 and 15 close intermittently an. electric circuit comprising disk 7 shaft 5, support 6, wire 16, battery 17, electro-magnet 18.and wire '19, support 9, shaft 10 and arm 14. Electro-niagnet 18 acts upon one end of a spring 20 which is fixed to" an overhanging fixed support 21. The free end of this spring rests upon a rod 22 which passes through the coil of the magnet and carries at its lower end an armature 23. When the magnet is energized the armature 23 and rod 22 are, lifted and the free end of hair spring 20 is forced toward the overhang 21 and a point on the hair spring midway between the supports moves transversely in the same manner as a similar point on the hair spring of the watch under test. This last-named mechanism may be called a comparator. 26 is a handle attached to the electro-magnet by which the comparator may be held upon a watch or otherwise as desired. 24 is the hair spring of the watch 25 under test.

In practice the spring 20 is held directl over spring 24 and the motor 1 being starte magnet 18 by means of thearmature 23 and rod 22 causes the spring to be intermittently compressed when contacts 8 and 15 close the circuit. The movements of the hair spring 24 of the watch 25 may conveniently becompared by a lens 27 mounted in a tube 28.

Fig. 5 shows my comparator as used when the test is to be madeby aural instead of optical means. In this figure 29 and 30 are members of a dummy spring-controlled escapement which is actuated by the rod 22 of the electro-ma et 18. The rod 22 engages the free end of a lever 31 the other end of which carries the escapement lever 29. In this case each time that contact 8 touches 15 the e'lectro-magnet is ener ed and the rod 22 operates the lever 31. e sound is carri d f om the ele tive-magnet to one ear of cal.

- lution of arm 12. While this has been found the observer by tube 32 and the sound from the watch 23 under test to the other ear of the observer by means of tube 33. The ends 34 of these tubes are provided with suitable receivers, one of'these receivers being located over the dummy eseapement and the other over the watch escapement, and the other ends 35 with suitable ear pieces.

In the form of my invention above described the revolving disk carrying the terminal 8 makes each revolution in absolutely the same time and in a time which is a known definite function of the time indicated by a standard chronometer" and also in a time more or less commensurate with the interval between two ticks'of the device the time of which is to be regulated. If the arm 14 is stationary the terminals 8', 15 will contact to close a circuit for an instant at absolutely equal intervals of time and if the spring 20 is imposed on the Watch spring 24 as shown in Fig. 4 and viewed through the lens 27. the movements of the two springs will be in phase and the length of the intervals which should exist between the ticks of a watch if the watch is operating to. show the correct time, will be identi- Now if the movements of the two springs are not in phase, the arm is rotated slowly in one direction or the other to determine if the watch is running fast or slow. If it is necessary to move it in the direction in which the disk is revolved to secure this synchronism, the time interval between the closing of the electrical circuit is increased and such movement of the arm will indicate that the watch is running slow; if the arm is revolved in a direction opposed to that of the disk the time interval will be shortened showing that the watch is runnin fast. The watch may be immediately adjusted until complete synchronism is secured, this taking but a few moments.

It therefore the tick of the watch and the closing of the circuit are simultaneous and the two remain absolutely simultaneous over a reasonable period of time, the watch is keeping time with the chronometer. If, however, after the tickof the watch and the time of the first contact have been made simultaneous it is found-that the arm must be revolved to maintain "the synchronism, then it is a simple matter' to ascertain whether the watch is fast or slow andby how much.

It is obvious that, if a watch is fast, the movements of the arm must be made uniformly in the direction opposed to that in .which the disk is revolving and if slow in the direction in which the disk is revolving.

I have provided and shown knob 11 which can be turned by hand to produce this revoto provide a simple and efi'ective means of revolving arm 12, it is clear that the same movement can be produced by a mechanism which can be easily controlled to give the desired movements of arm 12.

The operator may inform himself whether or not synchronism has been obtained by either the optical or aural means above described. Where there is a wide divergence between the length of the interval shown by the chronometer and that shown by the device under test, as in cases when new clocks or watches after assembling and before regulation are being tested, I have found that the reciprocating movement of a point on the hair spring of the balance'wheel is an admirable measure of the time interval. The comparator spring may be superposed on the watch spring and the rotative action of the two springs observed by a powerful magnifying glass or lens, with or without cross hairs. It is a simple operation to bring the two springs into phase by revolving the arm and, by a more or less rapid movement of the arm, to keep them in synchronism. It is apparent that by this method it is possible to compare differences in the lengths of the time intervals produced normally by the chronometer and by the watch under test with accuracy if the time of observation is made sufiiciently long, notwithstanding the fact that there may be an error amounting to a very small fraction of a second arising from the impossibility of detecting by the thousandth of a second, and that when lis tening binaurally a sound image lies toward that side of the head which first receives the sound. If the sounds reach the two ears so nearly simultaneously as to be less than 1X10" seconds apart the sound image is centered or seems to come from a point directly in front of the observer. This sense is common to man and is one that can be used with little or no conscious effort. I have utilized this method in observing the synchronism of the two devices in the manner shown in Fig. 5.

One of the tubes leads from the watch eseapement to say the right ear and the other from the dummy to the left ear. If the two escapements are in phase the sound image 1s centered. If not, adjustments can be made until synchronism is secured; using the arm the final adjustment sandth of a second and by turnin the arm to maintain the synchronism. e operation is simple and can be performed easily and rapidly. The use of the binaural method of timing is particularl useful in making f a watch which is running fairly closely with the chronometer, as with it the adjuster, after setting the arm to produce initial synchronism, no longer uses the arm, but changes the adjustment of the regulator of the watch to maintain the central position of the sound image.

' What I claim as my invention is 1. The method of measuring differences in the frequenciesof two oscillating systems which consists in bringing the two systems initially into simultaneous operation, 'adjusting one of the systems whereby-the: two s stems will be maintained in phase and etermining the difference in frequencies be tween --the two systems by measuring the amountof said ad'ustment.

2. In the regulatlon of a watch, the method of determining the difference of movement between the regulatable part in said watch and a corresponding part in an adjustable member of a. standard system of similar character, which comprises the adjustment of said adjustable member whereby the movements. of said parts will be maintained in phase and measuring the adjustment necessary to maintain such phase relation.

3. A method of measuring diiferences in the frequencies between one oscillating system and as second oscillating system comprising a standard member and an adjustable member, which consists inadjusting said ad'- justable member so that said second oscillatmg system is brought into phase with said first-named oscillating system andnoting the amount of said adjustment.

4. A method for bringing an oscillating system into phase with a second oscillatin system comprising a standard member an an adjustable member which consists in adjusting the adjustable member so that said second oscillating system will be brought into phase. with said first-named system for a definite-period of time, noting the amount of said adjustment and thereafter regulating the system to be adjusted. until \the two systems remain in phase without adjustment.

5. The method of adjusting the frequency of oscillations of anoscillating system-to bring it into phase with a second oscillating. system comprising a standard member and an adjustable member which consists in adjusting the normal movements of said ad-, justable member until said movements are in phase with the movements of the first-named system whereby the error in said first-named system maybe ascertained, and applging the amount of said adjustment to sald rstof which are controlled by standard chronometer, adjusting. the speed of the spring controlled by the chronometer until synchronism is obtained and noting'the amount and direction of the adjustment required to produce synchronism.

, 7 The method of standardizing an oscillating system which comprises the comparing of the mechanical movements of said system with the corresponding movements of a similar standard mechanism, altering the normal movements of said standard system until they synchronize with the corresponding movements of said oscillating system and noting the amount of adjustment required for such synchronizing, and applying a corresponding amount of adjustment to said oscillating system whereby it will move in synchronism with the normalmovements of said standard system.

8. In a device of the kinddescribed, a shaft and means for rotating it at a definite and uniform speed, said shaft carrying a contact, a second contact adjustable about the axis of said first contact, an electric circuit comprising said contacts and an electromagnet, a hair s ring and means for holding one end of it in xed position, and means operated by said elctro-magnet whereby the free end of said spring will be moved by the making or breaking of said contact.

9. In a device of the kind described, a shaft and means for rotating it at a definite and uniform speed, said shaft carrying a contact, a second contactadjustable about the axis of said first contact, an electric circuit comprising said contacts and an electro-magnet, and means operated by said electro-magnet whereby the function of ahair spring will said pointer whereby sai pointer will indicate on said disk the position of said contact.

- EZEKIEL WOLF.

second 

